How to change the tempo in your accompaniment track:

You have just downloaded your favorite aria but when you listen to it you realize that the tempo is too fast/slow. This is normal, the execution that
Opera-Karaoke proposes to you is certainly correct but is only one of the possible. If you think that it's absolutely necessary to change the tempo of the piano accompaniment
track you can follow this step-by-step tutorial. We remind you that if you modify the original MP3 file, you will loose the synchronisation with the Karaoke cd+g file, the "vocal line" track and the "diction track".
For this reason we strongly recommend not to overwrite the original file.

Download and install Audacity or another audio editor (the procedure will be about the same). The feature
you will need to use to achieve the result is usually called "Time Stretch" or "Change Tempo".

First of all, launch Audacity and, from the Menu "Project", select "Import Audio" and find the path in which your audio tracks are stored; in our case we select
the piano accompaniment track (for example "donnamobile.mp3"). Press the "Open" button; now the track is imported in your project.

You have to decide which region of our audio track needs to be edited, and you have to select it. If you want to change the tempo of the whole track,
go to the "Edit" menu and select "Select/All" (From the Keyboard "Control+A"). If you need to edit only a portion of your track, make sure that the
"Selection tool" () is highlighted and select the region by keeping down the left mouse button. Now your screen should appear like
this:

It's time to change the tempo of your track. From the menu "Effect", select "Change Tempo" (in other audio editing programs this function is
called "Time Stretch"); a window will open. In the "Percent change" box type positive values if you want to increase the tempo, negative if you want to decrease it.
Press the "Preview" button to check if you are satisfied with the result.

If you want to change the pitch of the whole track the procedure is almost the same. Select the whole track, from the menu "Effect" choose "Change Pitch": in the new
window select the number of Semitones that you want to change. Press the "Preview" button to check if you are satisfied with the result.

Play the whole track, if you think the result is good you can save your new track; go to the "File" menu and select "Export as WAV" ("Export as MP3" is good too), in the next window change the name of
the file (for example "Donnamobile_edited") and select "Save". Please don't overwrite the original piano accompaniment track!